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Why isn't sizeof for a struct equal to the sum of sizeof of each member?
...sing the cl.exe compier with the /Zp option.
Usually it is easier for the CPU to access data that is a multiple of 4 (or 8), depending platform and also on the compiler.
So it is a matter of alignment basically.
You need to have good reasons to change it.
...
Floating point vs integer calculations on modern hardware
...all of the data can reside in cache, where they can be quickly sent to the CPU. A very, very slow floating point operation that already has the data in cache will be many times faster than an integer operation where an integer needs to be copied from system memory.
I assume that you are asking thi...
Why do stacks typically grow downwards?
...n (because I didn't design them). My thoughts on the matter are that early CPUs got their original program counter set to 0 and it was a natural desire to start the stack at the other end and grow downwards, since their code naturally grows upward.
As an aside, note that this setting of the prog...
How do I read CSV data into a record array in NumPy?
...sing NumPy and Pandas, using pandas has a lot of advantages:
Faster
Less CPU usage
1/3 RAM usage compared to NumPy genfromtxt
This is my test code:
$ for f in test_pandas.py test_numpy_csv.py ; do /usr/bin/time python $f; done
2.94user 0.41system 0:03.05elapsed 109%CPU (0avgtext+0avgdata 50206...
Running multiple AsyncTasks at the same time — not possible?
...4 (API 19) the above fields are changed to this:
private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
private static final int CORE_POOL_SIZE = CPU_COUNT + 1;
private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;
private static final BlockingQueue<Runnable&g...
How to debug a GLSL shader?
...
You can't easily communicate back to the CPU from within GLSL. Using glslDevil or other tools is your best bet.
A printf would require trying to get back to the CPU from the GPU running the GLSL code. Instead, you can try pushing ahead to the display. Instead ...
Are Java static calls more or less expensive than non-static calls?
...n variable, and looping if not true.
I suppose the results will vary from CPU to CPU, and from JVM to JVM, so give it a try and see what you get:
import java.io.*;
class StaticVsInstanceBenchmark
{
public static void main( String[] args ) throws Exception
{
StaticVsInstanceBenchma...
C#中数组、ArrayList和List三者的区别 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...报错，且不能通过编译。这样就避免了前面讲的类型安全问题与装箱拆箱的性能问题了。
总结：
数组的容量是固定的，您只能一次获取或设置一个元素的值，而ArrayList或List<T>的容量可根据需要自动扩充、修改、删除或插入数...
Why is x86 ugly? Why is it considered inferior when compared to others? [closed]
...instructions. In the modern era this cost is becoming vanishingly small as CPUs become more and more limited by memory bandwidth than by raw computation, but many "x86 bashing" articles and attitudes come from an era when this cost was comparatively much larger.
Update 2016: Anandtech has posted a d...
How to measure time taken between lines of code in python?
...
If you want to measure CPU time, can use time.process_time() for Python 3.3 and above:
import time
start = time.process_time()
# your code here
print(time.process_time() - start)
First call turns the timer on, and second call tells you how m...